2001 Dodge Ram • 5.2L V8 Automatic • 147,000 miles

Ok, ive been having some brake issues with my truck. I took it to shop and they said it was the brake booster, got it replaced and adjusted, but the problem persists.
What its doing is this: Sometimes, not all the time, my brake pedal gets very firm, other times it goes down about 3-4", but when it gets hard I can onlt press it about 1-2". It does this at random times. The pressure I need to apply is not consistant. I believe the vacuum line if fine as when I press on the brake and turn engine on, it depresses. What else do I need to have checked?
January 14, 2014.

Cold be the abs module or the valve going into the booster they go bad sometimes. Also could be a master cylinder. Hav eit professionally bled otherwise you'll get an air pocket in abs unit.

Jan 14, 2014.